Method for managing storage space in a storage medium of a digital terminal for data storage according to a prioritized pixel transfer method

ABSTRACT

The invention relates to a method for managing storage space in a storage medium of digital terminal equipment for data storage according to the prioritized pixel transmission method, wherein multiple files with pixel groups sorted according to priorities are saved to the storage medium, wherein the method comprises the following steps:
     definition of a lower priority threshold value and an upper priority threshold value, wherein the priority threshold values indirectly indicate how much information content of a file is stored on the storage medium,   storage of files in the form of their pixel groups with the highest priority down to a priority corresponding to the selected lower priority threshold value until the available storage space of the storage medium has been filled,   increasing of the lower priority threshold value by one priority level; deletion of all pixel groups with a lower priority than that of the current priority threshold value on the storage medium,   use of the freed storage space in the storage medium for storing further data, the process being continued until the upper priority threshold is reached.

FIELD

The invention relates to a method for managing storage space in astorage medium of digital terminal equipment for data storage accordingto the prioritized pixel transmission method.

BACKGROUND

In multimedial mobile terminal equipment, such as. e.g., digitalcameras, mobile telephones, etc., the available storage space is verylimited. Multimedial data, such as e.g., image and video data, require alot of storage space, which is available in mobile terminal equipmentonly to a very limited degree. Once the maximally available storagespace has been filled, the user of the equipment must decide whether hewants to delete the old data content or refrain from storing new data.This fact shall be explained based on the example of a digital camera.Before taking a photograph, the user must adjust on the camera whichimage resolution the photograph is supposed to have. Modem digitalcameras offer multiple picture resolutions to chose from, e.g., 640×480,800×600 or 1024×768 image points (pixels). If the user selects a lowerresolution, e.g., 640×480 pixels, more photographs can be saved to thestorage medium of the camera. However, these photographs are then of alower quality. If the user opts for a higher resolution e.g., 1024×768,only a few photographs will fit on the storage medium. If the user wantsto continue taking photographs when the storage medium is full, he mustfirst delete photographs and free storage space by converting existingphotographs with a high resolution into photographs with a lowresolution and saving them as such. In both cases the available storagespace is not optimally used.

The explained example and its associated shortcomings are alsoapplicable to other mobile terminal equipment, e.g., to audio and videoterminals.

In EP 0 999 706 A2, a method is known for the dynamic management of astorage device for digital image data that is based on a so-called“embedded coding” of the bitstreams. in this method the image data issorted according to the importance of the image information, in such away that the bitstreams are coded such that the most important imageinformation is stored first and the least important image information isstored last. When the storage medium is full, additional imageinformation can be stored only in such a way that the least importantimage information of the image data that has been stored until then isdeleted, so that additional storage space is freed.

A similar method is revealed in U.S. Pat. No. 6,246,797 A, wherein a DCTtransform or wavelet transform is used in this case for coding of theimage data. If storage space is to be freed, the image information of acomplete image must be re-coded in each case, which requires arelatively large amount of computing effort.

U.S. Pat. No. 5,867,602 A reveals a method of coding digital data withthe aid of a reversible wavelet transform. An application of this methodfor storage space management of a storage medium is not described.

All methods known from the prior art do not use a coding method that isbased on a prioritized pixel transmission.

SUMMARY

The object of the invention consists of specifying a method whereby theavailable storage space in multimedial mobile terminal equipment can beoptimally used.

This object is met according to the invention in which a method formanaging storage space in a storage medium of digital terminal equipmentfor data storage according to the prioritized pixel transmission method,wherein multiple files with pixel groups sorted according to priorities(P1, P2, . . . , Pn) are saved to the storage medium, wherein the methodcomprises the following steps: a) definition of a lower prioritythreshold value (Pu) and an upper priority threshold value (Po), whereinthe priority threshold values indirectly indicate how much informationcontent of a file is stored on the storage medium; b) storage of filesin the form of their pixel groups with the highest priority (P1) down toa priority corresponding to the selected lower priority threshold value(Pu) until the available storage space of the storage medium has beenfilled; 3) increasing of the lower priority threshold value (Pu) by onepriority level; 4) deletion of pixel groups with a lower priority thanthat of the current priority threshold value (Pu) on the storage mediumas soon as additional storage space is needed on the storage medium; and5) use of the freed storage space on the storage medium for storingfurther data.

Advantageous further development and improvements of the invention willbecome apparent from the characteristics of the subclaims. Inparticular, the present invention provides a method in which it iscontinued, in dependence upon the required storage space, from methodstep b) until the upper priority threshold value (Po) is reached. Theinvention is further characterized in that the priority threshold values(Po, Pu) are adjustable by the user of the terminal equipment. Theinvention is further characterized in that the priority threshold values(Po, Pu) are permanently preset by the manufacturer of the terminalequipment. The invention is further characterized in that it is appliedonly to certain files selected by the user of the terminal equipment.The invention is further characterized in that the storage mediumcomprises multiple partial storage areas, wherein for each partialstorage area individual priority threshold values are definable. Theinvention is further characterized in that the data is subdividable intomultiply quality classes, wherein for each quality class individualpriority threshold values are definable. The present invention isfurther characterized in that the pixel groups are formed from digitizedscanning values of an audio signal. The invention is furthercharacterized in that the files contain image data, video data or audiodata. The invention is further characterized in that certain image/dataareas, such as faces or texts contained in the image can be changed bythe user in their priority allocation even subsequently.

The inventive method has as its basis the methods for compressing anddecompressing image data by means of prioritized pixel transmission,which are described in German patent applications DE 101 13 880.6(corresponds to PCT/DE02/00987) and DE 101 52 612.1 (corresponds toPCT/DE02/00995, now published as U.S. Patent Application Publication No.2004/0109609). In these methods, digital video data, for example, isprocessed, which consists of an array of individual image points(pixels), wherein each pixel has a pixel value that changes with timeand that describes color or brightness information of the pixel.According to the invention each pixel or each pixel group is allocated apriority and the pixels are stored in a priority array according totheir priority allocation. This array contains, at each moment in time,the pixel values that have been sorted according to the priorityallocation. According to this priority allocation, these pixels and thepixel values that have been used to calculate the priority allocationare transmitted and saved. A pixel receives a high priority if thedifferences in relation to its neighboring pixels are great. For thereconstruction process, the current pixel values in each case arereproduced on the display. The pixels that have not yet been transmittedare calculated from the pixels that have already been transmitted. Thesemethods are independent of the image resolution used. The imageresolution remains unchanged.

The revelation of applications DE 101 13 880.6 and DE 101 52 612.1 shallbe fully incorporated into the revelation of the present invention.

This means that in the case of the prioritized pixel transmission, thosepixel groups with the highest priority allocation, which contain theessential image information, are transmitted first. Thereafter, thepixel groups with the lowest priority allocation are transmitted, whichcontain negligible image information. The pixel groups with the lowestpriority allocation can thus be deleted without significantly impactingthe image quality.

The invention takes advantage of this fact.

In the mobile terminal equipment, e.g., in a digital camera, the imagedata is stored according to the invention in the form of prioritizedpixel groups in such a way that for the storage method at least twopriority threshold values for a minimum and maximum quality of the imagedata are specified. These priority threshold values may either bepermanently preset by the manufacturer of the terminal equipment orpreferably freely selected by the user.

Getting back to the example of the digital camera, all pictures areinitially taken with the maximal quality, i.e., the maximum quality,until the capacity limit of the storage medium has been reached, i.e.,the storage medium is full. During this process the images are read-inand saved according to the methods described in DE 101 13 880.6 and DE101 52 612.1, i.e., they are grouped into pixel groups and stored in theorder of their priority, that is to say their “image importance”.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates storage of image data with different priority valuesaccording to one embodiment of the invention;

FIG. 2 illustrates storage of image data in pixel groups with differentpriority values according to one embodiment of the invention;

FIG. 3 illustrates deletion of pixel groups from all stored image dataaccording to one embodiment of the invention; and

FIG. 4 illustrates storage space being freed by the method according tothe present invention.

DETAILED DESCRIPTION

An example embodiment of the invention will be explained based on thedrawings FIG. 1 through FIG. 4.

The image processing method operates, for example, with maximally sixpriority levels P1-P6. In practice it is possible to advantageouslyoperate with a significantly larger number of priority levels. Thepriority levels P1-P6 are assigned in each case to individual pixelgroups of the image data B1, B2, . . . , Bn to be stored. P1 correspondsto the highest, P6 to the lowest priority level. For storing acquiredimage data, the user selects for example P4 (maximum quality) as thelower priority threshold and P2 (minimum quality) as the upper prioritythreshold. Maximum quality means that more pixel groups are availableper image for reconstruction of the image than, in comparison, at theminimum quality.

According to FIG. 1, first the pixel groups whose priority is greater orequal to the lower priority threshold, i.e., the pixel groups with thepriority P1 through including priority P4 are stored for each newlyread-in image. The pixel groups with P5 and P6 are not stored. This isillustrated schematically in FIG. 2.

When the storage medium is full and the user now wishes to takeadditional pictures, all pixel groups that fall below certain prioritythresholds are deleted from the storage according to the invention,i.e., the pixel groups are deleted according to the reverse order oftheir importance. In accordance with the invention, the lower prioritythreshold is now raised from P4 to P3 so that from all images saved sofar, those pixel groups are deleted that fall below the prioritythreshold P3, that is to say the pixel groups with the priority P4. FIG.3 shows that from all stored image data B1, B2, . . . , Bn, the pixelgroups with the priority P4 were deleted. If there are, as in the shownexample, only 6 priority levels, approximately ⅙ of the availablestorage space is freed for new image data. This means, especially if,for example, only 1 new image is to be added, a significant loss ofquality in the existing images so that, in practice, a significantlyhigher number of priority levels is used so that always only therequired amount of storage space is freed without resulting in an overlylarge loss of quality in the existing images.

FIG. 4 shows that the storage space freed by this method can be used tostore new images. For example, new image data Bn+1 are saved in the formof pixel groups P1, P2, P3, which are saved to the corresponding freedstorage positions of the storage medium.

When the capacity limit of the storage medium has once more beenreached, the above-described method can be repeated until the lowerpriority threshold value corresponds to the upper priority thresholdvalue, in the present example P2. In the example, this means that thepriority threshold value is increased one level at a time from P4 to P3up to P2, depending on the number of images to be stored, so thatmatching storage space is freed for storing new images.

The user can optionally select, at the price of quality, which images orimage data are to be released for freeing new storage space. He can, forexample, block access to particularly important image data, so thatthese images remain intact at their full acquisition quality.

An improvement of the invention provides that the user can select, independence upon the type of equipment, different images with differentquality limits if required, or assign certain quality levels to theimages.

Also, certain image/data areas, such as faces or text contained in theimage, can subsequently be changed in the priority allocation by theuser. After regeneration of the image from the stored data, the user canmark in the image certain areas of particular interest to him, e.g.,faces. These marked areas are then stored with a higher priority alongwith the entire image.

This method advantageously provides for an optimized utilization of thetotal storage space of a storage medium in each case. The user does nothave to consider in advance, or not to the same degree as with theconventional image storage technology, which image resolution he wantsto use for which image. Depending on the number of saved images, theyare always present at the maximally possible image quality, which islimited by the available storage space.

The method described here can be applied not only for storing imagedata, but it is applicable in the same manner for audio or video data,provided that this data can be stored with the aid of the methods of theprioritized pixel groups.

According to one embodiment of the invention, the storage mediumcomprises multiple partial storage areas, wherein for each partialstorage area individual priority threshold values are definable. Theinvention is further characterized in that the data is subdividable intomultiply quality classes, wherein for each quality class individualpriority threshold values are definable. The present invention isfurther characterized in that the pixel groups are formed from digitizedscanning values of an audio signal. The invention is furthercharacterized in that the files contain image data, video data or audiodata. The invention is further characterized in that certain image/dataareas, such as faces or texts contained in the image can be changed bythe user in their priority allocation even subsequently.

1. A method for managing storage space in a storage medium of digitalterminal equipment for data storage of images according to a prioritizedpixel transmission method, wherein each image is stored in a data filethat consists of an array of individual image pixels, wherein each pixelhas a pixel value that describes the color or brightness information ofthe pixel, the method comprising the following steps: a. determining apriority value for each pixel of the array by calculating a pixeldifference value based on the given pixel value of the pixel in relationto the pixel values of a previously selected group of neighboringpixels, the priority values indicating the relative importance of therespective pixels to the image; b. grouping the pixels that are used forcalculating the priority value into a pixel group; c. sorting pixelgroups of the image array based on their priority values; d. savingmultiple data files with pixel groups sorted by priority (P₁, P₂, . . ., Pn) on the storage medium; e. selecting a lower priority thresholdvalue (Pu) and an upper priority threshold value (Po), wherein thepriority threshold values indirectly indicate how much informationcontent of a file is stored on the storage medium, the lower prioritythreshold means that a greater number of pixel groups are available forreconstruction of the image, and the upper priority threshold means thata fewer number of pixel groups are available for reconstruction of theimage; f. storing files in the form of their pixel groups havingpriority values between the highest priority (P₁) and a prioritycorresponding to the selected lower priority threshold value (Pu) untilthe available storage space of the storage medium has been filled; g.increasing the lower priority threshold value (Pu) by one prioritylevel; h. deleting pixel groups with a lower priority than that of thecurrent priority threshold value (Pu) on the storage medium whenadditional storage space is needed on the storage medium to create freedstorage space; and i. using the freed storage space in the storagemedium for storing further data.
 2. A method as set forth in claim 1,further comprising the steps of repeating, in dependence upon therequired storage space, steps b)-e) until the upper priority threshold(Po) is reached.
 3. A method as set forth in claim 1, wherein thepriority threshold values (Po, Pu) are adjustable by the user of theterminal equipment.
 4. A method as set forth in claim 1, wherein thepriority threshold values (Po, Pu) are permanently preset by themanufacturer of the terminal equipment.
 5. A method as set forth inclaim 1, wherein the method steps are applied only to certain filesselected by the user of the terminal equipment.
 6. A method as set forthin claim 1, wherein the storage medium comprises multiple partialstorage areas, wherein for each partial storage area individual prioritythreshold values are definable.
 7. A method as set forth in claim 1,wherein the data is subdividable into multiple quality classes, whereinfor each quality class individual priority threshold values aredefinable.
 8. A method as set forth in claim 1, wherein the pixel groupsare formed from digitized scanning values of an audio signal.
 9. Amethod as set forth in claim 1, wherein the files contain image data,video data or audio data.
 10. A method as set forth in claim 1, whereincertain image/data areas, such as faces or texts contained in the imagecan be changed by the user in their prioritization even subsequently.11. A method as set forth in claim 2, wherein the priority thresholdvalues (Po, Pu) are adjustable by the user of the terminal equipment.12. A method as set forth in claim 11, wherein the method steps areapplied only to certain files selected by the user of the terminalequipment.
 13. A method as set forth in claim 12, wherein the storagemedium comprises multiple partial storage areas, wherein for eachpartial storage area individual priority threshold values are definable.14. A method as set forth in claim 13, wherein the data is subdividableinto multiple quality classes, wherein for each quality class individualpriority threshold values are definable.
 15. A method as set forth inclaim 14, wherein the pixel groups are formed from digitized scanningvalues of an audio signal.
 16. A method as set forth in claim 15,wherein the files contain image data, video data or audio data.
 17. Amethod as set forth in claim 16, wherein certain image/data areas, suchas faces or texts contained in the image can be changed by the user intheir prioritization even subsequently.
 18. A method as set forth inclaim 2, wherein the priority threshold values (Po, Pu) are permanentlypreset by the manufacturer of the terminal equipment.
 19. A method asset forth in claim 18, wherein the method steps are applied only tocertain files selected by the user of the terminal equipment.
 20. Amethod as set forth in claim 19, wherein the storage medium comprisesmultiple partial storage areas, wherein for each partial storage areaindividual priority threshold values are definable.